Scientific method

The Scientific method is the single most successful methodology for verifying knowledge that the human mind has created. At its core is is the idea that the truth value of a hypothesis, theory, or concept is best determined by its ability to make falsifiablepredictions that can be tested against an empirical reality.
This means higher powers, spirits, demons or gods cannot be included in a hypothesis since there is no empirical evidence for them, further adding Supernatural concepts to hypotheses creates unnecessary complications.

3) Compare the hypothesis with empirical evidence, (usually experimental evidence often supported by mathematics)--this step is the reason why a hypothesis or theory has to be falsifiable). Have the experiment reproduced by third parties.

4) If the hypothesis is in agreement with the evidence it becomes a theory, if it doesn't, return to step 2.

A prediction forms a new hypothesis, making the cycle repeat.
Additionally, confirmation of these predictions strengthens the original theory.

steps 3 to 5 are omitted from the process in pseudosciences such as Intelligent Design (where step 3 would be impossible) and homeopathy.
However because steps 1 and 2 are still there, to some laymen, pseudosciences may mistakenly appear to have scientific authority.